\documentclass{article}
\usepackage[x11names, rgb]{xcolor}
\usepackage[utf8]{inputenc}
\usepackage{tikz}
\usetikzlibrary{snakes,arrows,shapes}
\usepackage{amsmath}
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\usepackage[active,tightpage]{preview}
\PreviewEnvironment{tikzpicture}
\setlength\PreviewBorder{0pt}%
\usetikzlibrary{automata}%

\begin{document}
\pagestyle{empty}
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\enlargethispage{100cm}
% Start of code
\begin{tikzpicture}[>=latex',join=bevel,]
\tikzstyle{every state}=[draw=blue!50,very thick,fill=blue!20]%
\node (q0) at (105bp,282bp) [state] {$q_{0}$};
  \node (q2) at (105bp,194bp) [state] {$q_{2}$};
  \node (q5) at (33bp,106bp) [state] {$q_{5}$};
  \node (q1) at (177bp,194bp) [state] {$q_{1}$};
  \node (q4) at (105bp,106bp) [state] {$q_{4}$};
  \node (q7) at (177bp,106bp) [state] {$q_{7}$};
  \node (q6) at (105bp,18bp) [state] {$q_{6}$};
  \node (q3) at (33bp,194bp) [state] {$q_{3}$};
  \draw [->] (q2) ..controls (88bp,167bp) and (79bp,153bp)  .. (70bp,142bp) .. controls (66bp,137bp) and (61bp,132bp)  .. node[auto] {$\overline{c}$} (q5);
  \draw [->] (q2) ..controls (111bp,165bp) and (116bp,152bp)  .. (124bp,142bp) .. controls (130bp,134bp) and (138bp,127bp)  .. node[auto] {$a$} (q7);
  \draw [->] (q5) ..controls (57bp,77bp) and (73bp,57bp)  .. node[auto] {$a$} (q6);
  \draw [->] (q1) ..controls (160bp,167bp) and (150bp,153bp)  .. (141bp,142bp) .. controls (137bp,138bp) and (133bp,133bp)  .. node[auto] {$\overline{c}$} (q4);
  \draw [->] (q1) ..controls (177bp,164bp) and (177bp,148bp)  .. node[auto] {$\overline{b}$} (q7);
  \draw [->] (q4) ..controls (105bp,76bp) and (105bp,60bp)  .. node[auto] {$\overline{b}$} (q6);
  \draw [->] (q7) ..controls (153bp,77bp) and (137bp,57bp)  .. node[auto] {$\overline{c}$} (q6);
  \draw [->] (q0) ..controls (81bp,253bp) and (65bp,233bp)  .. node[auto] {$\overline{c}$} (q3);
  \draw [->] (q0) ..controls (105bp,252bp) and (105bp,236bp)  .. node[auto] {$\overline{b}$} (q2);
  \draw [->] (q0) ..controls (129bp,253bp) and (145bp,233bp)  .. node[auto] {$a$} (q1);
  \draw [->] (q3) ..controls (20bp,167bp) and (17bp,154bp)  .. (19bp,142bp) .. controls (19bp,139bp) and (20bp,136bp)  .. node[auto] {$\overline{b}$} (q5);
  \draw [->] (q3) ..controls (40bp,165bp) and (45bp,152bp)  .. (53bp,142bp) .. controls (59bp,134bp) and (67bp,128bp)  .. node[auto] {$a$} (q4);
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\end{tikzpicture}
% End of code

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\end{document}
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